Help with process for determining development times

Discussion in 'B&W: Film, Paper, Chemistry' started by Jeff Bannow, Apr 1, 2009.

  1. Jeff Bannow

    Jeff Bannow Member

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    So, in the process of setting up my new darkroom I am moving from stainless steel inversion tanks to a Jobo CPP2 with lift. I have used a Jobo before and am familiar with its operation, though this particular Jobo is new to me.

    I have some Pyrocat HD that I would like to test for development time. For various reasons, I would prefer to shoot at box speed and adjust development to match. I am however a little confused on how to do this. My plan was to shoot a normal scene say 4 times, then process each one for a different amount of time and go with the one that looks good.

    I don't have a densitometer or sensitometer. I'm not exposing using the zone system. I see that Richard Ritter offers a service - Film testing - but I'm not sure if this would help me or how I would use it.

    I guess what I need is a beginner's tutorial on determining development speed.
     
  2. Paul

    Paul Member

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    What film will you be using and what printing process? What metering technique?
     
  3. Jeff Bannow

    Jeff Bannow Member

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    Film - mostly Acros 100 and FP4+. Printing - Silver gelatin via condenser head. Metering - incident metering.

    Thanks.
     
  4. Paul

    Paul Member

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    Jeff,

    If you are comfortable using BTZS metering techniques, you could start with the silver times that Clay Harmon has posted here. That will put you very close to the right times for FP4 and all you would have to do is shoot and see how it goes and adjust a bit here and there.

    -Paul
     
  5. Jeff Bannow

    Jeff Bannow Member

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    Never used BTZS metering, but I found some starting times that look good. I figured I could just look at the test negs on my light table, but I'm not sure if I need something more scientific.
     
  6. Paul

    Paul Member

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    BTZS metering is easy. Take a reading in the shadows and a reading in the bright area, subtract the low EV from the high EV and add that to 5. Thus, if your bright area is an EV 15 and the shadow area an EV 13, you have a SBR of 7 (which is "normal" in zone system terms). Then look at the times recommended for that SBR and develop accordingly. You could also look at Phil Davis's book.
     
  7. Jeff Bannow

    Jeff Bannow Member

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    That doesn't sound too hard at all. My meter has a spot meter on it, I just never delved into using it.
     
  8. Jim Noel

    Jim Noel Member

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    Your idea of shooting at box speed and altering development will likely work with the films you mention. However, many films will be underexposed by 2/3 of a stop or more if used at box speed. Since correct exposure is based on shadow values, and development primarily alters highlight values it is necessary to determine your correct EI prior to determining correct development time.
     
  9. keithwms

    keithwms Member

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    Clip tests.
     
  10. Paul

    Paul Member

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    If you use BTZS to determine exposure you should use an incident meter, not a spot meter.
     
  11. ic-racer

    ic-racer Member

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    Jeff,

    There are a lot of ways to do it. Your way will work fine, but don't just look at the negatives, print them on your favorite paper and see which looks best.

    Another tried-and-true method you may want to try is Fred Picker's, which is based on a Zone VIII printing to 'just off white.'

    To do it you expose a uniform target to Zone VIII (using your previously established exposure index). Fill the rest of the roll with pictures and be sure to shoot a blank frame also.
    Develop the roll for your 'first guess' time.
    In the darkroom with your favorite paper and paper developer (Grade 2 filter if using MG), put the blank frame in the enlarger. Expose a test strip, looking for the first step that is just maximum black (don't look too hard). Now, using the same exposure (or summed multiple exposure sequence) put the Zone VIII negative in the enlarger and don't touch anything. Then make a print with half the paper covered. If you see just 'off-white' in the exposed part your development time for that roll should be fine. If the paper is all white, then decrease development by 20% for the next roll. If your exposed half is too dark, then increase development by 20%.

    There are quite a few places for errors; for example the EI you use will change things, or your determination of 'just black' and 'just white' can significantly alter the results and if your initial 'uniform target' is not uniform it will mess things up. So always double check if your development times you are getting seem way out of line with what others are using.

    BTW if you need any film speed checks (highly recommended before determining development time) I'll be glad to check any negatives you send to me with a calibrated densitometer...it will cost you ice cream though :wink: PM for details.
     
    Last edited by a moderator: Apr 1, 2009
  12. Jeff Bannow

    Jeff Bannow Member

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    That doesn't seem too hard, and I can certainly afford ice cream! Should I mail the ice cream with the negatives or is a visit to Country Maid in order? :smile:
     
  13. largely

    largely Member

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    Jeff,
    I use Barry Thornton's method ( see barrythornton.com) and it's worked perfectly for me. My negs have improved a hundredfold since I read the advice offered there.
    good luck,

    Larry
     
  14. ic-racer

    ic-racer Member

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    I hear there is a good ice cream shop in Harbor Springs...

    Check your PM.